Syngas formation in methane flames and carbon monoxide release during quenching

Journal Article · Tue Feb 15 00:00:00 EST 2011 · Combustion and Flame

DOI:https://doi.org/10.1016/J.COMBUSTFLAME.2010.08.016· OSTI ID:21401357

Weinberg, Felix; Carleton, Fred; Houdmont, Raphael ^[1]; Dunn-Rankin, Derek; Karnani, Sunny ^[2]

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1. Department of Chemical Engineering, Imperial College, London (United Kingdom)
2. Department of Mechanical and Aerospace Engineering, University of California, Irvine (United States)

Following a recent investigation into chemi-ionization and chemiluminescence during gradual aeration of small, laminar methane flames, we proposed that partial oxidation products, or syngas constituents, formed in the pre-flame zone well below the luminous region, were responsible for the observed effects. We therefore map temperature, CO, and H{sub 2} for geometries and conditions relevant to burners in domestic boiler systems, to assess the potential hazard of CO release into the ambient atmosphere, should any partial quenching occur. CO concentrations peaks of 5.5 volume % are recorded in the core surrounding the axis. Appreciable CO concentrations are also found in the absence of added air. Experiments on various burner port geometries and temperatures suggest that this is not due to air entrainment at the flame base but to diffusion from zones closer to the flame. Next, quenching surfaces such as grids, perforated plates and flame trap matrices of different metals are progressively lowered into the flame. To avoid flow line distortion, suction aspirates the quenched products. The highest emission rate occurs with the quenching plane some 4 mm above the burner; further lowering of the quenching surface causes flame extinction. The maximum CO release is close to converting 10% of the CH{sub 4} feed, with some variation with quenching material. Expressing this potential release in terms of, e.g. boiler power, predicts a potentially serious hazard. Results of numerical simulations adequately parallel the experimental sampling profiles and provide insights into local concentrations, as well as the spatially resolved CO flux, which is calculated for a parabolic inlet flow profile. Integration across the stream implies, on the basis of the simulation, a possible tripling of the experimental CO release, were quenching simply to release the local gas composition into the atmosphere. Comparison with experiment suggests some chemical interaction with the quenching surface. (author)

• OSTI ID: 21401357
• Journal Information: Combustion and Flame, Vol. 158, Issue 2; Other Information: Elsevier Ltd. All rights reserved; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CARBON MONOXIDE
METHANE
LAMINAR FLAMES
SPATIAL DISTRIBUTION
HYDROGEN
COMPUTERIZED SIMULATION
HOUSES
BURNERS
EMISSION
BOILERS
HAZARDS
METALS
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE DISTRIBUTION
OXIDATION
ZONES
FLAME EXTINCTION
DIFFUSION
IONIZATION
MAPS
MATRICES
PLATES
SAMPLING
TRAPS
VARIATIONS
Syngas